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Corrections for PMDG FDE in FS2004

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Here's what I have done to preserve the FS2002 PMDG flight dynamics in FS2004. It involves some modification to the B737-700.air and aircraft.cfg files...these are for the -700.FS2004 ignores the wing incidence and twist parameters, resulting in about 0.5 deg more nose-up attitide for a given AoA in FS2004, and there is a significant increase in induced drag resulting from this and other changes in the way FS2004 does flight dynamics. After the mods, I have pitch, trim, and cruise fuel flows consistent between FS2002 and FS2004.RegardsBob ScottATP IMEL Gulfstream II-III-IV-V L-300Washington, D.C.========================================MODIFICATIONS:In B737-700.air:Table 1101 Cmo = 0.10 (was -.00488)Table 1205 HStab Incidence = -1.0 (was -.5, may not have effect in FS2004)Table 404:X Y-3.141600 -0.240000-2.748900 0.359900-2.346423 0.500000-1.953723 0.359900-1.561023 -0.070000-0.164723 -0.078000-0.094943 -0.040000-0.042583 0.067000-0.025123 0.1290000.009777 0.2461500.027227 0.3432100.201757 1.2658200.210487 1.3028800.220957 1.3350000.232306 1.3500000.245396 1.3600000.257614 1.3450000.267213 1.3200000.283794 1.2200000.341390 0.7600000.372805 0.5600000.393749 0.4650000.428656 0.3500000.463563 0.2740000.550829 0.2040001.580577 -0.0285002.356200 -0.3600003.141601 -0.240000In aircraft.cfg file:-airplane_geometry-wing_incidence = 0.00 (was 1.0)wing_twist = 0.0 (was -2.75)htail_incidence = -1.0000 (was -0.5000)-flight_tuning-induced_drag_scalar = 0.71

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Hi Bob,Took a look at your work and did made the changes to the aircraft.cfg. However the same files in my FS9 version airfile don't contain 1104 or the 404 tables with reference to Cmo or the complete 404 inputs.Where and how did you find the tables.ThanksBob Johnson

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Bob; Cmo is in table 1101 (Primary Aerodynamics). Table 404 (Aoa vs CL) is certainly there...it's required for any model. I dumped the airfile using the AirUpdate program (available at www.mudpond.us), modified the table 404 figures there, and reinserted the changes back. You can also manually edit the points in AirEd or AirfileManager...only the X coords changed (shifted right by .008 radians). The Cmo value is about halfway down table 1101, and you'll see it with either AirfileManager or AirEd with Herve' Sor's updated AirEd.ini file.CheersBob ScottATP IMEL Gulfstream II-III-IV-V L-300Washington, D.C.

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One more noteIn AirEd, Cmo is labeled Pitch moment coefficient at AoA=0 (CoG offset)The value shown in AirEd is 2048*Cmo...so you need to enter 205, not 0.1If using airfilemanager, you enter 0.1 directly...it does the factoring for you.CheersBob

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Thanks Bob,I will now go back and make some changes to the airfile since it was changed with the update.BobKDEN

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Hi Bob,I downloaded the airupdate program, thanks and made the changes in the 404 tables, plus all the other changes in the air file and aircraft.cfgHowever using AirEd, the line you gave me: The value shown in AirEd is 2048*Cmo...so you need to enter 205, not 0.1does not quite read what you said, there is no 2048*Cmo, but the current value is 0.1. I am going to change that value to 205. I hope that is correct. Please let me knowThanks for everything BobCheersBob Johnson

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Bob, right after I sent the previous post, I tried to make the change from 10 to 205, but AirEd, won't let me make that change. Is that OK?CheersBob

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Bob; Don't know what's happening to you with AirEd there...the original value (using AirEd 1.52 here) is -10...I changed it to +204 without a problem. I expand table 1101 by left-clicking on it, then select Cmo by clicking on the value (pitch moment at AoA=0 (CoG Offset)) and enter 204 in the text box that openes up and press . If that doesn't succeed, I'd suggest you go find airfilemanager...it's point-and-click. If you use it, the default value is something like -0.00488 and the corrected new value (it does the conversions for you) is +0.10RegardsBob ScottATP IMEL Gulfstream II-III-IV-V L-300Washington, D.C.

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Would someone from PMDG allow you to post these changes so we could download them? Or are they working on this problem themselves?

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This is one man's opinion, not to belittle anyone's efforts but messing with air files should never be done by people who do not have a complete knowledge of all aspects of the air file. There was a "Taxi Mod" for PIC that was claimed did not effect anything but the thrust for taxi, well I pointed out that this was not true and got flamed for doing so, but in the end anyone using PIC could tell that it did effect much more than taxi thrust. So be carefull, I would encourage you not to mess with it... [h4]Best Wishes,Randy J. Smithhttp://img.villagephotos.com/p/2003-8/196432/winglets_lg.jpg [h3] AMD XP 2200 |MUNCHKIN 512 DDR RAM |ECS[/b ][i] K7S5A MB[/i] |GF2 MX 32 MEG and still runs GOOD!|WIN XP PRO |MITSUBISHI DIAMOND PLUS 91 19"[/h3]

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The question for PMDG is have they investigated FDE differences due to FS8 vs. FS9? Apparently Bob Scott found some differences, and it would be nice to hear from PMDG if they have or plan to investigate his findings.Lee Hetherington (KBED)

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>This is one man's opinion, not to belittle anyone's efforts>but messing with air files should never be done by people who>do not have a complete knowledge of all aspects of the air>file. No - it is much bigger than just one man's opinion. This issue is well documented in the MSFS forum. A proposal of required corrections has also been well documented in the MSFS forum.Note that the very first statement made in regards to the change was "... this is what was done to preserve the flight model ...". That statement alone indicates that some degree of behavioral difference has been noticed.The only way to validate such claims is to do the research, make changes, run the tests, document the findings, conduct the analysis - and do it again, and again, and again ... until you either achieve the desired results, settle for an acceptable compromise, or, through these efforts refute the original claims and move on to the next problem. The process is long, meticulous, oftentimes extremely frustrating, but it is the only way that issues with this degree of complexity can be resolved.In the interest of furthering the fidelity and accuracy of the flight model - experimentation is required. We should be commending those that have the interest, motivation and capability to do so. We should not be rejecting their efforts or discrediting them through insinuation. Progress does not come from remaining idle and accepting less than perfection. The art of engineering is to achieve that "perfect balance" between the optimal goals and what is practically achieveable given the constraints of the environment.Besides, Mr. Scott knows his stuff. I for one commend him on what he has brought to light!-michael

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That all sounds good except for one important factor, he does not know this aircraft like the developers. He does not have a clear kowledge of what effects what in this file, and,why or how. Plus who says PMDG are not looking into this or have been?? [h4]Best Wishes,Randy J. Smithhttp://img.villagephotos.com/p/2003-8/196432/winglets_lg.jpg [h3] AMD XP 2200 |MUNCHKIN 512 DDR RAM |ECS[/b ][i] K7S5A MB[/i] |GF2 MX 32 MEG and still runs GOOD!|WIN XP PRO |MITSUBISHI DIAMOND PLUS 91 19"[/h3]

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OK folks; I had to stop writing and delete the first draft of my answer to Randy Smith's post. Here's take 2. Randy, take a look through the MSFS Aircraft and Panel Design Forum. Please let me know if my work there leads you further to believe I don't have a "complete knowledge of all aspects of the air file." Fact is, I've been hip-deep in exploring the inner workings of the FS9 FDE since it was released. The lessons I've learned in that effort are what I put to work in writing a number of FD modifications for airfiles in FS2004. Give me some specific shortcomings that result from my suggested mods, not unfair parallels to a foodfight you once fought over some other guy's mod to some other airfile some time in the past. The changes to FS2004's FDE affected PMDG's careful work on the FS2002 737-700 FDs. I applied the knowledge I have gained on the differences in new FS2004 FDE to correct performance back to what PMDG coded into its FS2002 FD. Where, I ask, is there a better solution to be had? Let me know...I want it, too. In the meantime, I offered it up as free advice to my friends here. For the record, I have over 30 years of real-world experience in everything from sailplanes to supersonic jets to heavy 4-engine jet transports, including over a thousand hours of jet instructor time. I also earned a four-year college degree in computer science and worked my way through college as an application programmer. I feel quite comfortable in my qualifications to translate the differences between a computer simulation and the real thing. It causes me some pain to have my work publicly criticized by a guy that: a) hasn't even tried it out yet and has nothing concrete to offer in critique, and :( probably has more posts in this forum than actual flying hours in his logbook. The choice is yours: try the mod or stick with the status quo...machts nichts bei Mir.RegardsBob_____________________________R. J. Scott, BS, MS, MSS, MBAAirline Transport PilotInstrument Airplane Multi-Engine LandG-1159 G-IV G-V L-300Commercial Priveleges Single Engine Land

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Bob, I am not saying for you not to explore what you feel is lacking in FS9, but this would apply to ALL payware aircraft correct? But you must know that once someone uses your *mod*, PMDG will not offer any support for problems they might encounter. Please don't get personal on me Bob, you will be going beyond friendly discussion and you seem like a nice guy, please don't take offence at one who does not 100% agree with you. Anyone who developes anything for flight sim will get questions-opinions that are not always very nice or the developer feels offence at, it's the by-product of the business. When I say that you do not know THIS aircraft, this is correct, this matters not how long you have been simming, flying or programming. PMDG has a man who is very capable to fix any problems with this airfile. That being said, if you want to test this out in ALL aspects of this flight model and provide the results have at it, I too have been around the block to know that just claiming something no matter what their creditials are does not mean it will be without issues. EDIT: Please don't miss-quote me Bob, I said "He does not have a clear kowledge of what effects what in this file"[h4]Best Wishes,Randy J. Smithhttp://img.villagephotos.com/p/2003-8/196432/winglets_lg.jpg [h3] AMD XP 2200 |MUNCHKIN 512 DDR RAM |ECS[/b ][i] K7S5A MB[/i] |GF2 MX 32 MEG and still runs GOOD!|WIN XP PRO |MITSUBISHI DIAMOND PLUS 91 19"[/h3]

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> That all sounds good except for one important factor, he>does not know this aircraft like the developers. He does not>have a clear kowledge of what effects what in this file,>and,why or how. OK - whatever. I'm not interested in discussion based upon unsubstantiated speculation, and I can see this discussion is quickly becoming a dead-man's spiral.-michael

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Sorry to start this :(Anyway, I am no flight dynamics expert, but importing any fde from fs2002 to 2004 seems to change things a litte. I was just curious if pmdg was looking into this or not.

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Randy; No way, Bucko--there was no mis-quote...that quote came straight out of your first post on this thread. Let me point out that there's a major difference between disagreeing with somebody on a point, and impugning their knowledge and/or abilities. You dumped twice now on what you think I know, not on what I've said or done. Let me offer that, although I did not write this air file, I very possibly *may* have better knowledge of how this air file interacts with the significantly different FS2004 FDE than the man (men?) who *did* write it--for FS2002. I know from hours of testing that the post-mod FD performs much closer to the original FS2002 specs than the un-modded FS2002 FD simply ported over to FS2004. Try it...then tell me I'm wrong. But you'd better bring some facts to the table, not "he didn't write it so he can't possibly understand it" hyperbole. Bottom line, for the second time you've not engaged here with anything of substance...but you've several times now suggested that I can't possibly know what this airfile is all about. Show me where I've erred. Demonstrate for us that the unmodified FD in FS2004 performs closer to the original FS2002 FD than my modded version. You can't, because it doesn't. You've attempted to cast a dark cloud over my knowledge, skill, and ability--not my work. On what basis do you suggest that I do not have a "clear kowledge (sic) of what effects (sic) what in this file?" Let me offer that it appears to me the designer himself may not have a clear knowledge of what affects what in the air file *in FS2004*...understandable in the absence of an SDK on this new FDE. Expertise is established by your works...the real meat you put on the table. You've offered up nothing but ungrounded hysteria here so far. Refute me with facts, or back me up, or get out of the way so we can get these dynamics fixed up right in FS9.RegardsBob ScottATP IMEL Gulfstream II-III-IV-V L-300Washington, D.C.

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No way, Bucko--there was no mis-quote...that quote came straight out of your first post on this thread. Ok, but I was still talking about THIS AIRCRAFT'S air file. "This is one man's opinion, not to belittle anyone's efforts but messing with air files should never be done by people who do not have a complete knowledge of all aspects of the air file. " Read it again, I'm sure you can see what I am getting at. Let me point out that there's a major difference between disagreeing with somebody on a point, and impugning their knowledge and/or abilities. You dumped twice now on what you think I know, not on what I've said or done Really? Where is that?. Saying that you don't know the why or what about THIS airfile and how it WORKS with this AIRCRAFT is not casting a dark cloud over your knowledge. Bottom line, for the second time you've not engaged here with anything of substance...but you've several times now suggested that I can't possibly know what this airfile is all about. Show me where I've erred. Ah classic here, it's not up to me to prove OR disprove your claims Bob, that's for you to provide. I see you are offended easy there Bob, I will leave you to this thread and wish you much luck. [h4]Best Wishes,Randy J. Smithhttp://img.villagephotos.com/p/2003-8/196432/winglets_lg.jpg [h3] AMD XP 2200 |MUNCHKIN 512 DDR RAM |ECS[/b ][i] K7S5A MB[/i] |GF2 MX 32 MEG and still runs GOOD!|WIN XP PRO |MITSUBISHI DIAMOND PLUS 91 19"[/h3]

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Bob, the new AirEd ini file took care of the problem.ThanksBob J

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Hi Randy and Bob,I hope that my questions did not start any type "fued" between you guys. I understand that air files are a very touchy subject within the MSFS community. I once critized the air file on another plane development team and started WW3. To this day I know that the air file was pure BS (grin).I respect the work that PMDG did to the hilt. However, I did apply Bob's mod's to my PMDG airfile, and to my "dummy" knowledge, it has worked just as Bob said. The 737 does in fact fly with a much better AoA in FS9 about 1.5 degree nose up. I can't quantify the fuel burn yet, but it does look "in the ball park".Randy, I know that you have worked hard on the development of the PMDG NG and Brovo to you and the team. Bob Scott has added IMHO a nice little update to the FDE. I would hope that the FDE developer on the PMDG team would take the time to just take a look at what Bob did and evaluate it. Sometimes all of us can learn a little from each other, I know I sure do.Thanks to BOTH of you guys, as long as any debate helps makes the PMDG 737 even better all is good. By no means attack each other, we are all on the same team, not like some other folks that used to rock and roll on being NEGATIVE.CheersBob

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I really did not mean to offend Bob, it could have come off that way but really was not my intent so I hope he does not hold it against me. I am not so proud not to say when I was wrong and I feel I spoke all the wrong words, sorry bud. Yes these type of things do bring about battles at times but I think we don't have to follow that pattern. Bob seems to be at a level that others I have seen were not, he does know a lot about airfiles. I don't use FS9 for my serious flying, it's sure pretty and all but still don't feel at home in the sim just yet. I like mods I swear! hehe, it's just I deal with other aspects like below ;)http://forums.avsim.net/user_files/33585.jpg [h4]Best Wishes,Randy J. Smithhttp://img.villagephotos.com/p/2003-8/196432/winglets_lg.jpg [h3] AMD XP 2200 |MUNCHKIN 512 DDR RAM |ECS[/b ][i] K7S5A MB[/i] |GF2 MX 32 MEG and still runs GOOD!|WIN XP PRO |MITSUBISHI DIAMOND PLUS 91 19"[/h3]

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Randy, please don't take this the wrong way, but perhaps you should stop trying to be PMDG in this forum and let PMDG respond to issues like this. I think that your initial responses, although well intentioned to caution folks about messing around with things, instead squelches improvement.Maybe PMDG is addressing these issues, maybe not. How can we know? PMDG is fairly quiet these days from our perspective. I don't blame them given some of the recent forum activity, but I also don't blame people for addressing issues themselves and trying to help others.Lee Hetherington (KBED)

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